Review
of
the
liter
a
ture
revealed
th
a
t
increases
in
ovulation
r
a
te,
e
i
ther
genetic
or
environmental
in
nature,
could
increase
the
number
of
embryos
at
about
day
30
of
gestation,
but
only
slight
increases
in
litter
size
at
birth
occurred.
This
suggested
that
to
increase
litter
size,
it
would
be
necessary
to
understand
how
uterine
capacity
affected
litter
size.
A
model
of
litter
size
was
developed
based
on
ovulation
rate,
potential
embryonic
viability,
and
uterine
capacity.
The
model
partitions
prenatal
mortality
into
embryonic
and
fetal
phases,
with
uterine
capacity
interacting
with
ovulation
rate
and
potential
embryonic
viability
to
cause
fetal
mortality.
Based
on
the
model,
selection
for
litter
size
is
equivalent
to
selection
for
potentially
viable
embryos
and
uterine
capacity
by
independent
culling
levels.
The
consequences
of
this
finding
are
discussed
and
various
selection
strategies
are
simulated.
The
design
of
an
ongoing
selection
experiment
for
ovulation
rate
and
uterine
capacity
in
swine
is
presented
and
opportunities
for
future
research
are
discussed
Reviewoftheliteraturerevealedthatincreasesinovulationrate,eithergeneticorenvironmentalinnature,couldincreasethenumberofembryosataboutday30ofgestation,butonlyslightincreasesinlittersizeatbirthoccurred.Thissuggestedthattoincreaselittersize,itwouldbenecessarytounderstandhowuterinecapacityaffectedlittersize.Amodeloflittersizewasdevelopedbasedonovulationrate,potentialembryonicviability,anduterinecapacity.Themodelpartitionsprenatalmortalityintoembryonicandfetalphases,withuterinecapacityinteractingwithovulationrateandpotentialembryonicviabilitytocausefetalmortality.Basedonthemodel,selectionforlittersizeisequivalenttoselectionforpotentiallyviableembryosanduterinecapacitybyindependentcullinglevels.Theconsequencesofthisfindingarediscussedandvariousselectionstrategiesaresimulated.Thedesignofanongoingselectionexperimentforovulationrateanduterinecapacityinswineispresentedandopportunitiesforfutureresearcharediscussed
การแปล กรุณารอสักครู่..
Review
of
the
liter
a
ture
revealed
th
a
t
increases
in
ovulation
r
a
te,
e
i
ther
genetic
or
environmental
in
nature,
could
increase
the
number
of
embryos
at
about
day
30
of
gestation,
but
only
slight
increases
in
litter
size
at
birth
occurred.
This
suggested
that
to
increase
litter
size,
it
would
be
necessary
to
understand
how
uterine
capacity
affected
litter
size.
A
model
of
litter
size
was
developed
based
on
ovulation
rate,
potential
embryonic
viability,
and
uterine
capacity.
The
model
partitions
prenatal
mortality
into
embryonic
and
fetal
phases,
with
uterine
capacity
interacting
with
ovulation
rate
and
potential
embryonic
viability
to
cause
fetal
mortality.
Based
on
the
model,
selection
for
litter
size
is
equivalent
to
selection
for
potentially
viable
embryos
and
uterine
capacity
by
independent
culling
levels.
The
consequences
of
this
finding
are
discussed
and
various
selection
strategies
are
simulated.
The
design
of
an
ongoing
selection
experiment
for
ovulation
rate
and
uterine
capacity
in
swine
is
presented
and
opportunities
for
future
research
are
discussed
การแปล กรุณารอสักครู่..